Phased Array used in the Industry

Phased array is widely used for non-destructive testing in several industrial sectors, such as construction, pipelines, and power generation. This method is an advanced NDT method that is used to detect discontinuities i.e. cracks or flaws and thereby determines component quality. Due to the possibility to control parameters such as beam angle and focal distance, this method is very efficient regarding the defect detection and speed of testing. Apart from detecting flaws in components, phased array can also be used for wall thickness measurements in conjunction with corrosion testing. Phased array can be used for the following industrial purposes:

Inspection of Welds
Thickness measurements
Corrosion inspection

Flaw detection

Ultrasonic phased array systems can potentially be employed in almost any test where conventional ultrasonic flaw detectors have traditionally been used. Weld inspection and crack detection are the most important applications, and these tests are done across a wide range of industries including aerospace, power generation, petrochemical, metal billet and tubular goods suppliers, pipeline construction and maintenance, structural metals, and general manufacturing. Phased arrays can also be effectively used to profile remaining wall thickness in corrosion survey applications. The benefits of phased array technology over conventional UT come from its ability to use multiple elements to steer, focus and scan beams with a single transducer assembly. Beam steering, commonly referred to sectorial scanning, can be used for mapping components at appropriate angles. This can greatly simplify the inspection of components with complex geometries. The small footprint of the transducer and the ability to sweep the beam without moving the probe also aids inspection of such components in situations where there is limited access for mechanical scanning. Sectorial scanning is also typically used for weld inspection. The ability to test welds with multiple angles from a single probe greatly increases the probability of detection of anomalies. Electronic focusing permits optimizing the beam shape and size at the expected defect location, thus further optimizing probability of detection. The ability to focus at multiple depths also improves the ability for sizing critical defects for volumetric inspections. Focusing can significantly improve signal-to-noise ratio in challenging applications, and electronic scanning across many groups of elements allows for C-Scan images to be produced very rapidly.

For the detection and sizing of flaws in new and in-services welds and components Matrix offers the semi-automated Time of Flight Diffraction (TOFD) ultrasonic technique.

Technique:
TOFD inspection employs two longitudinal wave (L-wave) angle beam transducers arranged symmetrically opposite facing each other, straddling the weld or base material under test. One probe acts like a transmitter of ultrasonic energy while the other probe receives the ultrasound energy. The transducer, pulser, and amplifier characteristics are selected to generate as broad distribution of energy as possible over the material under test providing full weld coverage. A single-axis scan (that is, along the weld), with a position encoder records the position of the weld and enables the display of digital images in real time.

Capabilities

• TOFD defect detection does not depend on the defect orientation, in contrast to the pulse echo technique.
• In contrast to the radiography method, planar defects and cracks, which are not perpendicular to the measured surface, can be detected.
• Defect height can be exactly determined.
• Higher POD improves risk reduction and calculation.
• The inspection results are immediately available, as is a permanent record and a permanent print as longitudinal or transversal projection of the weld is available.
• Because of the high test speed the costs are less than those for radiography for wall thickness above 25 mm.
• The inspection can be performed above200° C.
• Versatile and portable equipment

Applications

• New and existing welds
• Defect monitoring
• Stress Corrosion Cracking
• Weld root erosion surveys

Internal rotary inspection system (IRIS) is an ultrasonic method for the nondestructive testing of pipes and tubes. The IRIS probe is inserted into a tube that is flooded with water, and the probe is pulled out slowly as the data is displayed and recorded. The ultrasonic beam allows detection of metal loss from the inside and outside of the tube wall. IRIS is commonly used in boilers, heat exchangers, and fin-fan tubes.